This is a proposal for LBNL's Terrestrial Ecosystem Science SFA on soil carbon cycling. In this SFA, we conduct basic research on soil carbon turnover, storage, and loss. The products of this SFA will include process-level understanding and data needed to improve ecosystem models of ecosystem-climate feedbacks, sequestration, and land use change. We apply a combination of field and laboratory experiments, natural abundance 14C and isotopically labeled substrates, advanced imaging, and microbial ecology to study:
o Decomposition and stabilization of aboveground and belowground plant inputs
- Blodgett Forest. In 2001, we placed 13C/15N-labeled roots and needles in Sierra Nevada soils. We will use the final 10-year collection, and earlier analyses, to investigate the influence of litter type, soil depth, and microbial community on decomposition rates, pathways, and compound-specific stabilization.
- EBIS-AmeriFlux. We are studying decomposition of 14C-labelled leaves and roots at four AmeriFlux sites, as part of the multi-National Lab Enriched Biosphere Isotope Study. We are responsible for the soil density fractionations and quantifying 14C-based turnover times.
o Physical and microbial processes of black carbon (BC) degradation. We are investigating BC decomposition in incubations and started a field study in 2009, the first to directly quantify BC degradation rates in situ and identify BC decomposers.
o Mechanisms of long-term soil organic matter stabilization. We are working to bridge from molecular mechanisms of carbon stabilization to multi-scale biogeochemical models, integrating experimental data and numerical simulation methods. Our goal is to improve terrestrial carbon models based on new conceptual understandings of organic matter dynamics.